This is a multicenter, rising-dose, placebo-controlled Phase Ib study to evaluate the safety, tolerability and antiviral activity of 4 weeks of treatment w/ a new nucleoside reverse transcriptase inhibitor-fozivudine todoxil-in patients with HIV infection. The primary goal of the study is to identify doses that are well tolerated and produce measurable antiviral activity, and ultimately to det-ermine whether fozivudine is less toxic, better tolerated, and at least as active against HIV as zidovudine (AZT).